Telephone system



Oct. 8, I929. MATHlAs 1,730,617

' TELEPHONE SYSTEM Filed Nov. 25, 1927 Uel L 2 1W Maximilian T'I'Elhias Patented Oct. 8, 1929 UNITED STATES PATENT OFFICE MAXIMILIAN MATHIAS, 0F BERLIN, GERMANY, ASSIGNOR TO SIEMENS & HALSKE AKTIENGESELLSCHAIT, OF WEBNERWERK, SIEMENSSTAJJT NEAR BERLIN, GER- MANY TELEPHONE SYSTEM Application filed November 25, 1927, Serial No. 235,438, and in Germany February 12, 1927.

The invention relates to telephone systems, in which the release of a connection is initiated by alternating current impulses.

When in such installations alternating current of audible frequency is used forthe impulse transmission, there is the possibility of the connection being released by speech currents. Now the invention is to prevent such faults occurring in the service, this being achieved in a simple manner in that time switching devices, which are controlled by incoming alternating current impulses of audible frequency, prevent the connecting device being released when the duration of the impulses exceed or do not reach a certain time limit.

By way of example the invention is shown a system, in which the positioning of the switches is effected by an operator over a long junction line and the release is brought about automatically by an alternating current impulse of audible frequency when the K takes into use connection is. released at the operators position.

Referring now to the Figs. 1 and 2, only such apparatus in a system embodying the features of the invention has been shown as is necessary to enable the invention to be understood. Fig. 1 of the drawing shows theequipment at the opera tors position or originating end of the junction line and Fig. 2 shows the equipment at the automatic otfice or terminating end of the junction line.

In Fig. 1 the cord circuit is represented by the plug St, which when inserted into a jack the junction line having the leads La and Lb going to an automatic exchange. The junction line is isolated at both ends by means of voice current. repeaters, hence alternating current is used for the impulse transmission. In order that the alternating current impulses shall be efficiently repeated, alternating current of audible frequency is used'for the impulse transmission.

The method of operating will now be described with reference to the'drawing.

When the operator at the outgoing end'of the junction line has been requested to set up a connection with a subscriber of the drawing comprising automatic exchange reached over the junction line, she inserts the plug St into the jack K of Fig. 1. Thereby the relay B that is connected to the sleeve of the jack is energized, and at contact 1 b it closes a circuit for the relay 0 1 in series with the resistance W 1. 1n known manner the operator now switches over a not shown selecting switch, over which the impulse sender is connected to the leads of the plug. The alternating current impulses pass over the springs of the jack K, back contacts 15 a and 16 a to the primary winding of the repeater Ue they are then repeated over the leads La and Lb of the. junction line to the repeater Ue 2, Fig. 2, and thence over a chain of filters SK tuned to the frequency of the selecting impulses to the amplifier VSt. After being amplified, they then reach the alternating current relay R.- The latter at contact 5 r closes a circuit 7 for the relay J, which at the contact 6 j closes.

the circuit of the succeeding switches. each time an impulse is transmitted. At the same the winding of therelay Y. The latter is operated. At its contact 8 y it opens the circuit for energizing the relay C 2 and at the contact 20 1 it short circuits the winding of the relayG 2. But this cannot fall back, as the positioning impulses are of short duration and the armature of the relay C 2 falls backslowly owing to its winding being short circuited. Thus on receiving positioning impulses, the contact 7 j is opened before the relay C 2 has fallen back. When the relay Y operates, its contact 17 y prepares the circuit of the second time switching device, which comprises a relay Z and a resistance W 3 connected in parallel therewith. When the relay C 2 was operated, the contact 11 c 2 closed a circuit -for the release relay, which is connected to the testin and blocking lead and'belongs to the succee ing switch. When the relay Y is operated, its contact 14 y 100 bridges over the contact 11 2. The switch is then positioned in known manner.

At the end of the conversation, the operator withdraws the plug St from the jack K, Fig.

1, thus releasing the relay B, The latter at its contact 19 6 short circuits the winding of relay C 1 and at contact 3 b it closes a circuit for the relay A extending over the contact 4 0. Hence the relay'A is energized until the relay C 1 falls back, which it does slowly owing to the winding of C 1 being short cirv cuited. The alternating current source WQ, which has a definite audible frequency, is -connected over the contacts a and 16 a 15 to the junction line going to the automatic exchange. This alternating current impulse, which is long compared with the positioning impulses, energizes the relay B, Fig. 2, at the incoming end of the junction line and 20 thus a circuit for the relay J is closed at the contact 51. Relay'J switches over its contact 7 7', thereby short circuiting the winding of relay C 2 over the contacts 20 y and 22 a. At the same time the contact 18 j prepares 25 a circuit for: the relay Z, which. however, is only established when the relay 0 2 falls back and closes the contact 13 0 2. This circuit extends from earth over the contacts 18 j, 13 0 2, 17 y, winding of relay Z in parallel with resistance W 3 to battery and earth.

The relay Z attracts its armature slowly owing to the comparatively low ohmic resistance being connected in parallel with it. The releasing'impulse is of such length that it is terminated after the release of the relay C 2 and before the relay Z has operated. When the relay 0 2 then falls back, the contact 11 c 2 removes earth from the testing and blocking lead to the succeeding switch, but the latter 4 for the present remains connected up over the contact 14 3 However, the opening of the 'contact 12 c 2 interrupts the circuit of the relay-Y, hence this also falls back and effects the final removal of ground from the testing and blocking lead.

If the release impulse be too short, the relay C 2 is not short circ uited long enoughior it to fall back. On the other hand if the alternating current impulse be too long, the relay Z is operated as above described and thus a fresh circuit is established for the relays G 2 and Y over the contacts 20 y and 21 2. At the end of the current impulse, the contacts 7 j and 187' are opened, hence the relay Z falls back, while the locking circuit for the relays C 2 and Y is maintained over the contact From the foregoing it can be seen that" an means effective upon the cessation of the impulse for causing a redetermined operation of the mechanism, timing means for timing the duration of the impulse for a given period of time, additional timing means initiated into operation upon the expiration of said period of time for timing the duration of said im pulse for an additional period of time, and means efi'ective if the duration of the impulse is less than said first period of time or greater than both of said periods of time for rendering said first named means inefiective.

2. In an electroresponsive mechanism, means for receiving an impulse of current, two successively operated timing means each for 30 timing the duration of the impulse for a predetermined period of time, and means effective if the impulse of .current ceases during the timing by the second operated means for causing a predetermined operatioli' of the mechanism. i

3. In an electroresponsive mechanism, means for receiving an impulse of current, successively operated minimum and, maximum timing means for timingthe'duration of p the impulse, and means efiective of the impulse ceases after the operation of the minimum timing means and before the operation of the maximum timing means for causing the operation of the mechanism.

4. In" an .;electroresponsive mechanism, means for receiving: an. impulse ofcurrent, successively operated minimum and maximum timing means for timing the duration of the impulse, and means efiective if the duration of the impulse exceeds the minimum time and is less than the maximumtime for causing the operation of the mechanism.

5. In an electroresponsive mechanism,

means for receiving an impulse 6f current,

timing means for timing the duration of the impulse, and means controlled by the timing means and effective if the duration of the impulse exceeds a predetermined minimum amount of time and is less than a predeter- 11 mined maximum amount of time for causing the operation of the mechanism.

6. In an electroresponsive mechanism, means for receiving an impulse of current, means effective upon the cessation of the impulse for causing a predetermined operation of the mechanism, means for timing the duration of the impulse, and means eifective if the duration of the impulse exceeds a predetermined maximum period of-time for rendering the first named means and the mechanism unefiected by the impulse.

7. In an electroresponsive mechanism, means for reciving an impulse of current, means effective upon the cessation of the impulse for causing a predetermined operation of the mechanism, means for timing the duration of the impulse, and means efiective if the duration of the impulse exceeds a predetermined maximum period of time for rendering the first named means inefiective.

8. In an automatic switch wherein an impulse of current brings about the release of the switch, time delayed means for rendering the impulse of current ineiiective if its duration exceeds a predetermined period of time.

9. In an automatic switch, meansfor receiving an impulse of current, means effective upon the cessation of the impulse for causing the release of the switch, and means effective if the duration of the impulse exceeds a predetermined maximum period of time for rendering said first named means ineffective.

10. In a telephone system wherein the release of an existing connection is brought about by an impulse of alternating current of audible frequency impressed upon the talking conductors, means for preventing the release during the continuance of the impulse, and timing means for preventing the release if the duration of the impulse is less than a predetermined minimum or exceeds a predetermined maximum period of time.

11. In a telephone system wherein the release of an existing connection is brought about by an impulse of alternating'current of audible frequency impressed upon the talking conductors, a slow-to-respond relay controlled by the impulse of current, means effective upon the response of said relay for rendering the release of the mechanism dependent upon the cessation of the impulse,

and timing means eflt'ective a predetermined period of time after the response of said relay for preventing the release of the connection if the release has not already taken place.

12. In a telephone system wherein the re- 40 lease of an existing connection is controlled by an impulse of current, a slow-to-respond relay controlled by the impulse of current, means efiective upon the response of said relay for rendering the release of the connection dependent upon the cessation of the impulse, and timing means dependent upon'the continuance of theimpulse for a predetermined period of time for preventing the release of the connection by said impulse.

13. In a telephone system wherein the release of an existing connection is brought about b an impulse of current, means for preventing the release during the continuance of the impulse, and timing means for preventing the release if the duration of the impulse is less than the predetermined minimum or exceeds a predetermined maximum period of time.

In witness whereof, I hereunto subscribe my name this 26th day of October, A. D. 1927. Y

' V MAXIMILIAN MATHIAS. 

